phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('922367bcff519d415b9757d41c59af5f', -1, 1553032382, 1553032382, '12d0d396', -6, 0, 0)

Line : 187
File : sessions.php